Known is an image forming apparatus, such as a laser printer, provided with a process cartridge including a developing cartridge and a drum cartridge. The developing cartridge has a developing roller. The drum cartridge has a photosensitive drum. In the process cartridge, the developing cartridge is mounted in the drum cartridge. A combination of the developing cartridge and the drum cartridge as the process cartridge is integrally detachable from or attachable to a main casing of the image forming apparatus.
The drum cartridge has a drum frame for supporting the photosensitive drum. The drum frame has a cartridge accommodating portion in which the developing cartridge is accommodated. Further, the drum frame is provided with a roller. The roller is disposed at the cartridge accommodating portion.
The developing cartridge has a developing frame for supporting the developing roller. The developing frame is provided with a roller receiving portion for receiving the roller of the drum cartridge. The roller receiving portion is disposed at a position in confrontation with the roller provided at the drum frame when the developing cartridge is mounted in the drum cartridge.
When the developing cartridge is mounted in the drum cartridge, the developing frame is accommodated in the cartridge accommodating portion while the developing frame is brought into abutment with the roller. Further, the developing roller is brought into contact with the photosensitive drum. Hence, assembly of the developing cartridge relative to the photosensitive cartridge is achieved.
At this time, the roller provided at the drum frame is in abutment with the roller receiving portion provided at the developing frame. Abutment of the roller with the roller receiving portion regulates the movement of the developing frame, thereby positioning the developing cartridge relative to the drum cartridge.